feat: add Obsidian-style graph visualization

Implement force-directed graph view for visualizing note connections:

- Add graph data model parsing [[wiki-style links]]
- Implement Fruchterman-Reingold layout algorithm
- Create character-based canvas renderer with highlights
- Add interactive filtering by tag/folder
- Support navigation (h/j/k/l), zoom (+/-), and node selection
- New commands: :IdeaGraph, :IdeaGraphFilter

New files:
- lua/ideaDrop/ui/graph/{init,types,data,layout,renderer}.lua

Updated documentation in README.md, CHANGELOG.md, and llms.txt

CHANGELOG.md

@@ -7,6 +7,76 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+#### 🕸️ Graph Visualization (Obsidian-style)
+
+A new force-directed graph view that visualizes connections between your notes:
+
+- **Graph Data Model**: Parses `[[Note Name]]` wiki-style links from markdown files
+  - Supports `[[link|alias]]` format
+  - Builds bidirectional edges (undirected graph)
+  - Extracts tags and folder metadata for filtering
+
+- **Force-Directed Layout**: Implements Fruchterman-Reingold algorithm
+  - Spring forces attract connected nodes
+  - Repulsion forces prevent node overlap
+  - Gravity pulls high-degree nodes toward center
+  - Inverse gravity pushes orphan nodes to periphery
+  - Temperature-based cooling for stable convergence
+  - Supports both synchronous and animated layout modes
+
+- **Visual Rendering**:
+  - Dark background canvas for visual clarity
+  - Node size scales with degree (number of connections)
+  - Color-coded nodes: blue (default), purple (hubs), gray (orphans), red (selected)
+  - Semi-transparent edge lines showing connections
+  - Labels for selected and high-degree nodes
+
+- **Interactive Features**:
+  - `h/j/k/l` navigation between nodes
+  - `Enter` to open selected note in right-side buffer
+  - `t` filter by tag, `f` filter by folder, `r` reset filter
+  - `+/-` zoom in/out, `c` center graph
+  - `L` toggle labels, `?` toggle help overlay
+  - `q/Esc` close graph, `R` refresh graph data
+  - Smooth layout reflow when nodes are filtered
+
+- **New Commands**:
+  - `:IdeaGraph` - Opens the graph visualization
+  - `:IdeaGraph animate` - Opens with animated layout
+  - `:IdeaGraph refresh` - Refreshes graph data
+  - `:IdeaGraph close` - Closes the graph window
+  - `:IdeaGraphFilter tag <name>` - Filter graph by tag
+  - `:IdeaGraphFilter folder <name>` - Filter graph by folder
+
+- **New Configuration Options**:
+  - `graph.animate` - Enable animated layout (default: false)
+  - `graph.show_orphans` - Show nodes without connections (default: true)
+  - `graph.show_labels` - Show node labels by default (default: true)
+  - `graph.node_colors` - Custom colors by folder/tag
+
+- **New Files**:
+  - `lua/ideaDrop/ui/graph/types.lua` - Type definitions
+  - `lua/ideaDrop/ui/graph/data.lua` - Graph data model
+  - `lua/ideaDrop/ui/graph/layout.lua` - Force-directed layout algorithm
+  - `lua/ideaDrop/ui/graph/renderer.lua` - Character-based canvas renderer
+  - `lua/ideaDrop/ui/graph/init.lua` - Main graph module
+
+#### Other Additions
+
+- Added `CHANGELOG.md` to track project changes
+- Added `llms.txt` for AI/LLM context about the project
+- Added graph-related constants and settings in `constants.lua`
+- Added graph-related notification messages
+
+### Changed
+
+- Updated help documentation (`doc/ideaDrop.txt`) to include all commands: `IdeaBuffer`, `IdeaRight`, `IdeaTree`, tag commands, and search commands
+- Improved nvim-tree integration to preserve user's existing nvim-tree configuration
+- Updated `README.md` with comprehensive graph visualization documentation
+- Extended configuration options to include graph settings
+
 ### Fixed
 
 - **Critical**: Fixed glob pattern bug where files were not being found due to missing path separator (`/`) between directory and pattern in `list.lua`, `tags.lua`, and `search.lua`
@@ -15,16 +85,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed missing arguments in `sidebar.open()` call in `list.lua` which could cause unexpected behavior
 - Removed unused variable in `tags.lua` (`filename` in `show_files_with_tag` function)
 
-### Changed
-
-- Updated help documentation (`doc/ideaDrop.txt`) to include all commands: `IdeaBuffer`, `IdeaRight`, `IdeaTree`, tag commands, and search commands
-- Improved nvim-tree integration to preserve user's existing nvim-tree configuration
-
-### Added
-
-- Added `CHANGELOG.md` to track project changes
-- Added `llms.txt` for AI/LLM context about the project
-
 ## [1.0.0] - Initial Release
 
 ### Added